MWS 7.1: performance issues when searching tasks by business

Are there any performance issues when searching tasks by business data (e.g. search all tasks with a customerID=111)? In our case almost every tasklist access requires a query based on business data.

If I’m right the business data of a task is stored in a binary DB-field, which usually results in poor performance when selecting records based on that business data.

Is it possible to index business data search fields?

Best regards
Thomas